\documentclass[12pt]{article}

\usepackage{fontspec}
\usepackage{polyglossia}

\setmainlanguage{english}
\setotherlanguage{amharic}

\newfontfamily\amharicfont[Script = Ethiopic, Scale = 1.3]{[Abyssinica_SIL.ttf]}

\begin{document}

\title{Sample in Gǝ`ǝz}
\maketitle

\newdimen\savehsize
\savehsize\hsize

\long\def\test#1{\endgraf\hsize=1pt\noindent #1\endgraf\hsize=\savehsize}

\begin{amharic}
\lccode"1361="1361
\lccode"1362="1362
\pretolerance=-1
\hyphenpenalty=0
\hyphenchar\font=0
a እስመ፡አግዚአብሔር፡አምላክ፡ማእምር፡ውእቱ።እግዚአብሔር፡አስተደወ፡መንብሮ።ወአድከመ፡ቅሥተ፡ኀያላን።ወአቅነቶሙ፡ኀይለ፡ለድኩማን።ጽጉማን፡እክል፡ርኅቡ።ወርኁባን፡ጸግቡ።እስመ፡መካን፡ወለደት፡ሰብዐተ፡ወወለድሰ፡ስእነት፡ወሊደ፡እግዚአብሔር፡ይቀትል፡ወየሐዩ።ያወርድኒ፡ውስተ፡ሲእል፡ወየዐርግ።እግዚአብሔር፡ያነዲ፡ወያብዕል።ያኀስርሂ፡ወያከብር፡ዘያነሥኦ፡እምድር፡ለነዳይ።ከመ፡ያንብሮ፡ምስለ፡ዓበይ[ተ]~።

\test{a እስመ፡አግዚአብሔር፡አምላክ፡ማእምር፡ውእቱ።እግዚአብሔር፡አስተደወ፡መንብሮ።ወአድከመ፡ቅሥተ፡ኀያላን።ወአቅነቶሙ፡ኀይለ፡ለድኩማን።ጽጉማን፡እክል፡ርኅቡ።ወርኁባን፡ጸግቡ።እስመ፡መካን፡ወለደት፡ሰብዐተ፡ወወለድሰ፡ስእነት፡ወሊደ፡እግዚአብሔር፡ይቀትል፡ወየሐዩ።ያወርድኒ፡ውስተ፡ሲእል፡ወየዐርግ።እግዚአብሔር፡ያነዲ፡ወያብዕል።ያኀስርሂ፡ወያከብር፡ዘያነሥኦ፡እምድር፡ለነዳይ።ከመ፡ያንብሮ፡ምስለ፡ዓበይ[ተ]~።

}
\end{amharic}

\end{document}
